High pressure atomization

The pre-alloyed powder high-pressure atomization method is to pre-smelt various components of metals into alloys before sintering according to the designed carcass ratio, and then atomize and spray the powder to obtain the carcass powder with the required particle size. The atomization method can adopt water atomization or gas atomization. Air, nitrogen or argon can be used for gas atomization. The cooling rate is fast, the powder crystal grains are fine, the powder yield is high, and the cost is low. By adjusting the geometry of the nozzle, controlling the atomizing medium and other process parameters, metal powder of a certain size and shape (spherical or irregular shape) can be obtained.

Hydrometallurgy

Hydrometallurgy is to dissolve metal ions in water. The different element metals in the alloy (such as cobalt, copper, and iron subsalt solutions) are mixed in the correct proportions to form metal salts, and then precipitated and reduced to obtain very fine metal alloy powders. The particle size is below 10μm and the shape is The spherical porous agglomerate has good fluidity, compactness and good sintering performance, low sintering temperature, high hardness, good toughness, good holding power for diamond, and the made diamond tool cuts well.

Mechanical alloying

The mechanical alloying method is to place two or more metal powders in a high-energy ball mill. Through the long-term violent impact and collision between the powder particles and the grinding balls, the powder particles are repeatedly cold welded and fractured. The atoms in the powder particles diffuse to obtain alloyed powder.

excellent point

Pre-alloyed powder because each powder particle contains various metal elements that make up the alloy, the uniformity of the pre-alloyed powder composition is quite good. Since its eutectic point is much lower than the melting point of a single element in the alloy, during the sintering process, as long as the temperature reaches a point above the liquidus line of the pre-alloyed powder, the powder of the entire bonding metal component is melted, so the pre-alloyed powder has a low sintering degree , The use of pre-alloyed powder has the following significant advantages:

(1) The element distribution of pre-alloyed powder cutter head is more even than that of mechanically mixed powder cutter head, which fundamentally avoids component segregation;

(2) The pre-alloyed powder is fully alloyed and has a uniform structure, which greatly improves the compressive and flexural strength of the sintered product, and is easy to meet the performance requirements of the diamond product matrix;

(3) Pre-alloying greatly reduces the activation energy required for the diffusion of metal atoms during the sintering process, reduces the sintering temperature, shortens the sintering time, and avoids high-temperature diamond damage;

(4) The winding temperature is low. Reduce energy consumption and help reduce costs;

(5) Reduce the consumption of graphite molds, which is also conducive to reducing costs;

(6) The pre-alloyed powder has strong oxidation resistance and good sintering performance;

(7) The pre-alloyed powder matrix has high hardness and high impact strength;

(8) The pre-alloyed powder can hold the diamond according to the high, and the diamond protruding is high, thereby improving the sharpness of the diamond tool and prolonging the service life of the tool;

(9) In the case of the same cutting performance, the use of pre-alloyed powder can reduce the diamond concentration by 15% to 20%, making the production cost lower.

special point

Cobalt has many superior properties. For example, the diamond has good holding power, good sintering performance, high product density, and good compatibility with other metal powders. It has been widely used in diamond tool pre-alloy powder, but due to its high price, the supply channel Instability and strategic resource status in the aerospace, defense industry, cemented carbide and battery industries, in recent years the development and production of pre-alloy powder for diamond tools has mainly focused on substituting cobalt pre-alloy powder, which has the following characteristics:

(1) The chemical composition of pre-alloyed powder is developed towards low-cobalt and cobalt-free tires to further reduce costs and improve cost performance.

(2) The performance of the pre-alloyed powder is further improved and improved. For example, various methods are used to increase the density, impact strength and hardness of the pre-alloyed powder, reduce its sintering temperature, reduce the generation of brittle phases, and improve the uniformity of its composition;

(3) The product develops towards full pre-alloying of the carcass. Different from the pre-alloyed powder which mainly produced the basic pre-alloyed powder in the early stage of development, the pre-alloyed powders developed recently are all pre-alloyed powder carcasses for specific purposes and do not need to add other powders.